[flang][docs] Replace references to f18 in the docs with flang (Part 1)

In addition to the replacement, some light editing of the text was also
carried out. These edits primarily address issues of grammar and
style.

The remaining references to "f18" will be replaced in a later commit.

Author: tarunprabhu

flang/docs/AssumedRank.md

@@ -101,9 +101,9 @@ Assumed-rank dummies are also represented in the
 represent assumed-rank in procedure characteristics.
 
 ### Runtime Representation of Assumed-Ranks
-Assumed-ranks are implemented as CFI_cdesc_t (18.5.3) with the addition of an
-f18 specific addendum when required for the type. This is the usual f18
-descriptor, and no changes is required to represent assumed-ranks in this data
+Assumed-ranks are implemented as CFI_cdesc_t (18.5.3) with the addition of a
+Flang specific addendum when required for the type. This is the usual Flang
+descriptor, and no changes are required to represent assumed-ranks in this data
 structure. In fact, there is no difference between the runtime descriptor
 created for an assumed shape and the runtime descriptor created when the
 corresponding entity is passed as an assumed-rank.

flang/docs/C++17.md

@@ -6,7 +6,7 @@
   
 -->
 
-# C++14/17 features used in f18
+# C++14/17 features used in Flang
 
 ```{contents}
 ---
@@ -27,7 +27,7 @@ out the details of how our C++ code should look and gives
 guidance about feature usage.
 
 We have chosen to use some features of the recent C++17
-language standard in f18.
+language standard in Flang.
 The most important of these are:
 * sum types (discriminated unions) in the form of `std::variant`
 * `using` template parameter packs
@@ -41,7 +41,7 @@ in this list because it's not particularly well known.)
 ## Sum types
 
 First, some background information to explain the need for sum types
-in f18.
+in Flang.
 
 Fortran is notoriously problematic to lex and parse, as tokenization
 depends on the state of the partial parse;
@@ -57,7 +57,7 @@ a unified lexer/parser.
 We have chosen to do so because it is simpler and should reduce
 both initial bugs and long-term maintenance.
 
-Specifically, f18's parser uses the technique of recursive descent with
+Specifically, Flang's parser uses the technique of recursive descent with
 backtracking.
 It is constructed as the incremental composition of pure parsing functions
 that each, when given a context (location in the input stream plus some state),
@@ -73,7 +73,7 @@ of Fortran.
 
 The specification of Fortran uses a form of BNF with alternatives,
 optional elements, sequences, and lists.  Each of these constructs
-in the Fortran grammar maps directly in the f18 parser to both
+in the Fortran grammar maps directly in Flang's parser to both
 the means of combining other parsers as alternatives, &c., and to
 the declarations of the parse tree data structures that represent
 the results of successful parses.
@@ -87,10 +87,10 @@ The bounded polymorphism supplied by the C++17 `std::variant` fits
 those needs exactly.
 For example, production R502 in Fortran defines the top-level
 program unit of Fortran as being a function, subroutine, module, &c.
-The `struct ProgramUnit` in the f18 parse tree header file
+`struct ProgramUnit` in the Flang parse tree header file
 represents each program unit with a member that is a `std::variant`
 over the six possibilities.
-Similarly, the parser for that type in the f18 grammar has six alternatives,
+Similarly, the parser for that type in Flang's grammar has six alternatives,
 each of which constructs an instance of `ProgramUnit` upon the result of
 parsing a `Module`, `FunctionSubprogram`, and so on.
 
@@ -99,7 +99,7 @@ parse is typically implemented with overloaded functions.
 A function instantiated on `ProgramUnit` will use `std::visit` to
 identify the right alternative and perform the right actions.
 The call to `std::visit` must pass a visitor that can handle all
-of the possibilities, and f18 will fail to build if one is missing.
+of the possibilities, and Flang will fail to build if one is missing.
 
 Were we unable to use `std::variant` directly, we would likely
 have chosen to implement a local `SumType` replacement; in the

flang/docs/C++style.md

@@ -30,7 +30,7 @@ is clear on usage, follow it.
   is pretty good and comes with lots of justifications for its rules.
 * Reasonable exceptions to these guidelines can be made.
 * Be aware of some workarounds for known issues in older C++ compilers that should
-  still be able to compile f18. They are listed at the end of this document.
+  still be able to compile Flang. They are listed at the end of this document.
 
 ## In particular:
 
@@ -261,7 +261,7 @@ move semantics, member access, and comparison for equality; suitable for use in
 `std::variant<>`.
 * `std::unique_ptr<>`: A nullable pointer with ownership, null by default,
 not copyable, reassignable.
-F18 has a helpful `Deleter<>` class template that makes `unique_ptr<>`
+Flang has a helpful `Deleter<>` class template that makes `unique_ptr<>`
 easier to use with forward-referenced data types.
 * `std::shared_ptr<>`: A nullable pointer with shared ownership via reference
 counting, null by default, shallowly copyable, reassignable, and slow.
@@ -312,9 +312,9 @@ Consistency is one of many aspects in the pursuit of clarity,
 but not an end in itself.
 
 ## C++ compiler bug workarounds
-Below is a list of workarounds for C++ compiler bugs met with f18 that, even
-if the bugs are fixed in latest C++ compiler versions, need to be applied so
-that all desired tool-chains can compile f18.
+Below is a list of workarounds for C++ compiler bugs encountered when building
+Flang. Even if the bugs are fixed in latest C++ compiler versions, these need to
+be applied so that all desired tool-chains can compile Flang.
 
 ### Explicitly move noncopyable local variable into optional results
 
@@ -338,7 +338,7 @@ std::optional<CantBeCopied> fooOK() {
 }
 ```
 The underlying bug is actually not specific to `std::optional` but this is the most common
-case in f18 where the issue may occur. The actual bug can be reproduced with any class `B`
+case in Flang where the issue may occur. The actual bug can be reproduced with any class `B`
 that has a perfect forwarding constructor taking `CantBeCopied` as argument:
 `template<typename CantBeCopied> B(CantBeCopied&& x) x_{std::forward<CantBeCopied>(x)} {}`.
 In such scenarios, Ubuntu 18.04 g++ fails to instantiate the move constructor

flang/docs/Calls.md

@@ -529,7 +529,7 @@ PGI passes host instance links in descriptors in additional arguments
 that are not always successfully forwarded across implicit interfaces,
 sometimes leading to crashes when they turn out to be needed.
 
-F18 will manage a pool of trampolines in its runtime support library
+Flang will manage a pool of trampolines in its runtime support library
 that can be used to pass internal procedures as effective arguments
 to F77ish procedures, so that
 a bare code address can serve to represent the effective argument.
@@ -569,14 +569,14 @@ Fortran 2018 explicitly enables us to do this with a correction to Fortran
 2003 in 4.3.4(5).
 
 Last, there must be reasonably permanent naming conventions used
-by the F18 runtime library for those unrestricted specific intrinsic
+by Flang's runtime library for those unrestricted specific intrinsic
 functions (table 16.2 in 16.8) and extensions that can be passed as
 arguments.
 
 In these cases where external naming is at the discretion
 of the implementation, we should use names that are not in the C language
 user namespace, begin with something that identifies
-the current incompatible version of F18, the module, the submodule, and
+the current incompatible version of Flang, the module, the submodule, and
 elemental SIMD width, and are followed by the external name.
 The parts of the external name can be separated by some character that
 is acceptable for use in LLVM IR and assembly language but not in user

flang/docs/Character.md

@@ -6,7 +6,7 @@
 
 -->
 
-# Implementation of `CHARACTER` types in f18
+# Implementation of `CHARACTER` types in Flang
 
 ```{contents}
 ---
@@ -16,7 +16,7 @@ local:
 
 ## Kinds and Character Sets
 
-The f18 compiler and runtime support three kinds of the intrinsic
+The Flang compiler and runtime support three kinds of the intrinsic
 `CHARACTER` type of Fortran 2018.
 The default (`CHARACTER(KIND=1)`) holds 8-bit character codes;
 `CHARACTER(KIND=2)` holds 16-bit character codes;
@@ -108,12 +108,12 @@ The result of `//` may be used
 * as the value of a specifier of an I/O statement,
 * or as the value of a statement function.
 
-The f18 compiler has a general (but slow) means of implementing concatenation
+The Flang compiler has a general (but slow) means of implementing concatenation
 and a specialized (fast) option to optimize the most common case.
 
 ### General concatenation
 
-In the most general case, the f18 compiler's generated code and
+In the most general case, Flang's generated code and
 runtime support library represent the result as a deferred-length allocatable
 `CHARACTER` temporary scalar or array variable that is initialized
 as a zero-length array by `AllocatableInitCharacter()`

flang/docs/DoConcurrent.md

@@ -280,7 +280,8 @@ Specifically, an easy means is required that stipulates that localization
 should apply at most only to the obvious cases of local non-pointer
 non-allocatable scalars.
 
-In the LLVM Fortran compiler project (a/k/a "flang", "f18") we considered
+In the LLVM Fortran compiler project (now known as "flang", previously also
+known as "f18") we considered
 several solutions to this problem.
 1. Add syntax (e.g., `DO PARALLEL` or `DO CONCURRENT() DEFAULT(PARALLEL)`)
    by which one can inform the compiler that it should localize only

flang/docs/Extensions.md

@@ -84,7 +84,7 @@ end
   be "local identifiers" and should be distinct in the "inclusive
   scope" -- i.e., not scoped by `BLOCK` constructs.
   As most (but not all) compilers implement `BLOCK` scoping of construct
-  names, so does f18, with a portability warning.
+  names, so does Flang, with a portability warning.
 * 15.6.4 paragraph 2 prohibits an implicitly typed statement function
   from sharing the same name as a symbol in its scope's host, if it
   has one.
@@ -153,7 +153,7 @@ end
   that a call to intrinsic module procedure `ieee_support_halting` with
   a constant argument has a compile time constant result in `constant
   expression` and `specification expression` contexts. In compilations
-  where this information is not known at compile time, f18 generates code
+  where this information is not known at compile time, Flang generates code
   to determine the absence or presence of this capability at runtime.
   A call to `ieee_support_halting` in contexts that the standard requires
   to be constant will generate a compilation error. `ieee_support_standard`
@@ -366,7 +366,7 @@ end
 * The legacy extension intrinsic functions `IZEXT` and `JZEXT`
   are supported; `ZEXT` has different behavior with various older
   compilers, so it is not supported.
-* f18 doesn't impose a limit on the number of continuation lines
+* Flang doesn't impose a limit on the number of continuation lines
   allowed for a single statement.
 * When a type-bound procedure declaration statement has neither interface
   nor attributes, the "::" before the bindings is optional, even
@@ -553,7 +553,7 @@ end
 * Fortran explicitly ignores type declaration statements when they
   attempt to type the name of a generic intrinsic function (8.2 p3).
   One can declare `CHARACTER::COS` and still get a real result
-  from `COS(3.14159)`, for example.  f18 will complain when a
+  from `COS(3.14159)`, for example.  Flang will complain when a
   generic intrinsic function's inferred result type does not
   match an explicit declaration.  This message is a warning.
 
@@ -570,7 +570,7 @@ end
 
 ## Standard features that might as well not be
 
-* f18 supports designators with constant expressions, properly
+* Flang supports designators with constant expressions, properly
   constrained, as initial data targets for data pointers in
   initializers of variable and component declarations and in
   `DATA` statements; e.g., `REAL, POINTER :: P => T(1:10:2)`.
@@ -587,8 +587,8 @@ end
 * The standard doesn't explicitly require that a named constant that
   appears as part of a complex-literal-constant be a scalar, but
   most compilers emit an error when an array appears.
-  f18 supports them with a portability warning.
-* f18 does not enforce a blanket prohibition against generic
+  Flang supports them with a portability warning.
+* Flang does not enforce a blanket prohibition against generic
   interfaces containing a mixture of functions and subroutines.
   We allow both to appear, unlike several other Fortran compilers.
   This is especially desirable when two generics of the same
@@ -655,7 +655,7 @@ end
   treat them as references to implicitly typed local variables, and
   load uninitialized values.
 
-  In f18, we chose to emit an error message for this case since the standard
+  In Flang, we chose to emit an error message for this case since the standard
   is unclear, the usage is not portable, and the issue can be easily resolved
   by adding a declaration.
 
@@ -686,7 +686,7 @@ end
 
 * When a `DATA` statement in a `BLOCK` construct could be construed as
   either initializing a host-associated object or declaring a new local
-  initialized object, f18 interprets the standard's classification of
+  initialized object, Flang interprets the standard's classification of
   a `DATA` statement as being a "declaration" rather than a "specification"
   construct, and notes that the `BLOCK` construct is defined as localizing
   names that have specifications in the `BLOCK` construct.
@@ -703,7 +703,7 @@ end subroutine
   Other Fortran compilers disagree with each other in their interpretations
   of this example.
   The precedent among the most commonly used compilers
-  agrees with f18's interpretation: a `DATA` statement without any other
+  agrees with Flang's interpretation: a `DATA` statement without any other
   specification of the name refers to the host-associated object.
 
 * Many Fortran compilers allow a non-generic procedure to be `USE`-associated
@@ -729,7 +729,7 @@ module m2
 end module
 ```
 
-  This case elicits a warning from f18, as it should not be treated
+  This case elicits a warning from Flang, as it should not be treated
   any differently than the same case with the non-generic procedure of
   the same name being defined in the same scope rather than being
   `USE`-associated into it, which is explicitly non-conforming in the
@@ -747,7 +747,7 @@ end module
   symbols, much less appear in specification inquiries, and there are
   application codes that expect exterior symbols whose names match
   components to be visible in a derived-type definition's default initialization
-  expressions, and so f18 follows that precedent.
+  expressions, and so Flang follows that precedent.
 
 * 19.3.1p1 "Within its scope, a local identifier of an entity of class (1)
   or class (4) shall not be the same as a global identifier used in that scope..."
@@ -769,17 +769,17 @@ end module
   left-hand side for a pointer assignment statement, and we emit a
   portability warning when it is not.
 
-* F18 allows a `USE` statement to reference a module that is defined later
+* Flang allows a `USE` statement to reference a module that is defined later
   in the same compilation unit, so long as mutual dependencies do not form
   a cycle.
   This feature forestalls any risk of such a `USE` statement reading an
   obsolete module file from a previous compilation and then overwriting
   that file later.
 
-* F18 allows `OPTIONAL` dummy arguments to interoperable procedures
+* Flang allows `OPTIONAL` dummy arguments to interoperable procedures
   unless they are `VALUE` (C865).
 
-* F18 processes the `NAMELIST` group declarations in a scope after it
+* Flang processes the `NAMELIST` group declarations in a scope after it
   has resolved all of the names in that scope.  This means that names
   that appear before their local declarations do not resolve to host
   associated objects and do not elicit errors about improper redeclarations
@@ -862,11 +862,11 @@ print *, [(j,j=1,10)]
 
 * The Fortran standard doesn't mention integer overflow explicitly. In many cases,
   however, integer overflow makes programs non-conforming.
-  F18 follows other widely-used Fortran compilers. Specifically, f18 assumes
+  Flang follows other widely-used Fortran compilers. Specifically, Flang assumes
   integer overflow never occurs in address calculations and increment of
   do-variable unless the option `-fwrapv` is enabled.
 
-* Two new ieee_round_type values were added in f18 beyond the four values
+* Two new ieee_round_type values were added in Flang beyond the four values
   defined in f03 and f08: ieee_away and ieee_other. Contemporary hardware
   typically does not have support for these rounding modes;
   ieee_support_rounding calls for these values return false.

flang/docs/FortranForCProgrammers.md

@@ -304,7 +304,7 @@ Preprocessing behavior varies across implementations and one should not depend o
 much portability.
 Preprocessing is typically requested by the use of a capitalized filename
 suffix (e.g., "foo.F90") or a compiler command line option.
-(Since the F18 compiler always runs its built-in preprocessing stage,
+(Since Flang always runs its built-in preprocessing stage,
 no special option or filename suffix is required.)
 
 ## "Object Oriented" Programming

flang/docs/FortranIR.md

@@ -171,7 +171,7 @@ FIR is intentionally similar to SIL from the statement level up to the level of
 Program, procedure, region, and basic block all leverage code from LLVM, in much the same way as SIL. These data structures have significant investment and engineering behind their use in compilers, and it makes sense to leverage that work.
 
 * Pro: Uses LLVM data structures, pervasive in compiler projects such as LLVM, SIL, etc.
-* Pro: Get used to seeing and using LLVM, as f18 aims to be an LLVM project
+* Pro: Get used to seeing and using LLVM, as Flang aims to be an LLVM project
 * Con: Uses LLVM data structures, which the project has been avoiding
 
 #### Alternative: C++ Standard Template Library

flang/docs/GettingInvolved.md

@@ -41,7 +41,7 @@ Contributions to Flang are done using GitHub Pull Requests and follow the
 ### Flang Slack Workspace
 
 -   There is a Slack workspace dedicated to Flang.
--   There are a number of topic-oriented channels available (e.g., #driver, #f18-semantics, #fir).
+-   There are a number of topic-oriented channels available (e.g., #driver, #fir).
 -   Add yourself via the *[invitation link](https://join.slack.com/t/flang-compiler/shared_invite/zt-2pcn51lh-VrRQL_YUOkxA_1CEfMGQhw "title")*
 
 ## Calls